Various studies have been made for producing carbon fibers of high strength and high elasticity, using pitch as a starting material. However, composite materials (CFRP) obtained by using pitch-based carbon fibers are disadvantageous in that their compression characteristics, particularly, compressive strength, are markedly inferior in comparison with CFRP prepared by using polyacrylonitrile (PAN)-based carbon fibers. But even such PAN-based carbon fibers have not fully exhibited their features as thin materials utilizing the rigidity of carbon fibers because the compressive strength thereof is deteriorated with increase of elastic modulus.
For improving the compression characteristics of CFRP while utilizing the rigidity of carbon fibers, it is necessary to improve the compression characteristics of the carbon fibers themselves.
It is the object of the present invention to provide a process for producing pitch-based carbon fibers superior in compression characteristics.